Sikorsky S-76: Ask Nick Lappos
Transient limits are not normal limits....did the man say?
Please expound upon that for the audience....if the transient limits are in the limitations section and allows one to do certain exceedances without notation in the maintenance records then what is not "normal" about them?
All limitations are for normal operations. Operations that exceed the limitations are not "normal".
As to my view...."Limitations are for normal operations, Bloggs!" holds here....if you are crashing....on fire....or approaching the ground at an injurious rate.....then all bets are off and limitations become a reference to which you describe the exceedances.
Please expound upon that for the audience....if the transient limits are in the limitations section and allows one to do certain exceedances without notation in the maintenance records then what is not "normal" about them?
All limitations are for normal operations. Operations that exceed the limitations are not "normal".
As to my view...."Limitations are for normal operations, Bloggs!" holds here....if you are crashing....on fire....or approaching the ground at an injurious rate.....then all bets are off and limitations become a reference to which you describe the exceedances.
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had a similar one myself several years ago where it was either a sharp pull or watch the gear arrive through the airframe (flat approach to rig due cloud base, lost all lift as I got over the deck). The limits in the engineering manual are different to the flight manual. I think up to 230% all that is required is a look around to make sure the gearbox is still connected etc.. It was a while ago as I said but the engineers didn't seem too worried by the whole thing.
I stand by to be corrected by Nick
I stand by to be corrected by Nick
The Bell 212 Maintenance manual and the Boeing-Vertol CH-47 maintenance manual for sure have engineering limitations that exceed those listed in the flight manual.....which makes sense to me. That way, we ham handed guys that wear boxing gloves when we fly, are tricked into being a bit easier on the hardware. Something our benevolent employers appreciate because it helps their bonus packages at the end of the year.
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Bruised Armpit,
Sikorsky's position is stated in the flight manual and the maintenance manual. For transients, you can exceed the RFM limits, and still not have to do anything, as explained in the maintenance manual. When you pull an overtorque, write it up, and maintenance will disposition it.
The transients are to cover those times when you get an oops, and they prevent you from pulling a gearbox. Thus, they should not be counted on or purposefully used. As a rule, Sikorsky gearboxes cannot be harmed by the engine(s), because the box is stronger than the engine(s).
Let's face it, the limit is for daily use, the max transient is for a very small number of occurrences in the life of a box (once or twice).
I don't have the max transient limits at my fingertips for all the models of the 76, but the 76A's OEI max transient is about 155 torque for 15 sec, the DE transient is about 115 for 5 sec.
Sikorsky's position is stated in the flight manual and the maintenance manual. For transients, you can exceed the RFM limits, and still not have to do anything, as explained in the maintenance manual. When you pull an overtorque, write it up, and maintenance will disposition it.
The transients are to cover those times when you get an oops, and they prevent you from pulling a gearbox. Thus, they should not be counted on or purposefully used. As a rule, Sikorsky gearboxes cannot be harmed by the engine(s), because the box is stronger than the engine(s).
Let's face it, the limit is for daily use, the max transient is for a very small number of occurrences in the life of a box (once or twice).
I don't have the max transient limits at my fingertips for all the models of the 76, but the 76A's OEI max transient is about 155 torque for 15 sec, the DE transient is about 115 for 5 sec.
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Thanks for your replies. I completely agree about not intentionally using transients. Oops factor.
So, just so I can win an arguement....
Pulling between 100-115% torque Dual Engine (200-230% total transmission torque) for under 5 seconds is within the transient limits as per the RFM and no limit has been exceeded.
Correct?
Thanks
So, just so I can win an arguement....
Pulling between 100-115% torque Dual Engine (200-230% total transmission torque) for under 5 seconds is within the transient limits as per the RFM and no limit has been exceeded.
Correct?
Thanks
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SASless my humble apologies. What I meant to say is; Joe Average Aircraft Captain (JAAC) would not plan on using more than maximum torque.How ever on any given day should JAAC be a little off his game and approach down wind and carry a little extra speed then JAAC may need a little extra [transient]Torque to get stopped at the bottom.
But then again I may not know Jack.
But then again I may not know Jack.
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Bruised,
Yes.
Nigel, good question! The actual torque cannot be 155, because the engine only delivers 152 at worst worst case, so the Xmsn is OK by default! This was a subject for the original certification way back when, and is now part of S-76A lore! We can read ultra high torque on the instrumentation, if not on the cockpit gauge.
All this is good stuff, I know a 365 captain who had to change a transmission because he went to 107% torque for a few seconds, and got no relief from the factory.
Yes.
Nigel, good question! The actual torque cannot be 155, because the engine only delivers 152 at worst worst case, so the Xmsn is OK by default! This was a subject for the original certification way back when, and is now part of S-76A lore! We can read ultra high torque on the instrumentation, if not on the cockpit gauge.
All this is good stuff, I know a 365 captain who had to change a transmission because he went to 107% torque for a few seconds, and got no relief from the factory.
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I win from this post.
Nick,
you said,' The actual torque cannot be 155, because the engine only delivers 152 at worst worst case, so the Xmsn is OK by default! '
but,how's A++?
and IHL says, 'I think that 200% limit is for normal operations i.e. take-off
so you could have 1 engine at 104% and the other at 96% and that would be OK for take-off. Transient limits are notnormal ops they are transient.'
followed by IHL,I can use 115% for 1 engine and the other one at 85% for 2min for take-off. of course, normally it won't happend.
correct?
Nick,
you said,' The actual torque cannot be 155, because the engine only delivers 152 at worst worst case, so the Xmsn is OK by default! '
but,how's A++?
and IHL says, 'I think that 200% limit is for normal operations i.e. take-off
so you could have 1 engine at 104% and the other at 96% and that would be OK for take-off. Transient limits are notnormal ops they are transient.'
followed by IHL,I can use 115% for 1 engine and the other one at 85% for 2min for take-off. of course, normally it won't happend.
correct?
Last edited by HeliEagle; 21st Feb 2005 at 11:10.
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S-76 replacement
My company is looking to replace their ageing S-76++'s. What is the preferred choice of Ppruners as a replacement I wonder?
The operational environment is offshore, flying to rigs and accommodation vessels between 50 and 100 miles away from the main base. Seasonal temperature varies from -25C to +45C.
The operational environment is offshore, flying to rigs and accommodation vessels between 50 and 100 miles away from the main base. Seasonal temperature varies from -25C to +45C.
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I would have to say that the S76C+ would be hard to beat. For that matter, the A++ is hard to beat. Put those 1S1 engines in the A airframe, with no increase in allowable max gross weight, and you have loads of power. With C+s, you have a degree of commonality of parts, and both pilots and mechanics already familiar with the basic aircraft. It should be cheaper all around, rather than toss out all the spares and experience you alreadyi have.
The AB139 might be viable, but it hasn't been around long enough to tell.
The AB139 might be viable, but it hasn't been around long enough to tell.
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As a matter of interest what is a S76++, what is 'my company' with respect to a 'PPL' and, more importantly, where on earth does one find a single offshore province with a temperature range from -25C to +45C?
Avoid imitations
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Mars,
My thoughts exactly......
My thoughts exactly......
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The old suspicion showing through chaps 
"my company" as in my employer, my PPL is a plank one and for fun only, S-76++ cos that's what I've been told they are. I might have got a + wrong though.
The working limits for temperatures here are -40C to +40C but over the last few winters it's rarely gone below -25C but occasionally up to +45C. Think FSU rather than North Sea.
I'm asking about the options available as I am part of a team assessing the alternatives available to us. I thought that getting info from the people at the sharp end of the industry would be a sensible thing to do. Far better than reading manufacturer's brochures and listening only to the bean counters for example.
"my company" as in my employer, my PPL is a plank one and for fun only, S-76++ cos that's what I've been told they are. I might have got a + wrong though.
The working limits for temperatures here are -40C to +40C but over the last few winters it's rarely gone below -25C but occasionally up to +45C. Think FSU rather than North Sea.
I'm asking about the options available as I am part of a team assessing the alternatives available to us. I thought that getting info from the people at the sharp end of the industry would be a sensible thing to do. Far better than reading manufacturer's brochures and listening only to the bean counters for example.
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Why is somebody who obviously hasn't got a schmick about helicopters on the procurement panel?
Why is this person acting on information from somebody else who hasn't got a schmick about which machines they already have?
Where on this planet is there a seaside variation in temperature like that?
Reel the suckers in, and wind it up.
Why is this person acting on information from somebody else who hasn't got a schmick about which machines they already have?
Where on this planet is there a seaside variation in temperature like that?
Reel the suckers in, and wind it up.
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DD, strangely enough not everybody in a logistics department is an expert on helicopters. I have just started in the department and therefore am not, as yet, on intimate terms with the trucks, helicopters, hovercraft, tugs, barges, ice breakers, supply boats etc etc etc that we have / hire. I am however very familiar with the problems of operation and construction in the area and the restrictions that face the execution of transportation in this area which is why I'm on the team.
The hint as to the area remains FSU and, believe me, those temperature variations ARE real and not the worst around, Siberia gets at least 15C colder in the winter and nearly as hot in the summer.
The hint as to the area remains FSU and, believe me, those temperature variations ARE real and not the worst around, Siberia gets at least 15C colder in the winter and nearly as hot in the summer.
FSU (Former Soviet Union), prolly Kazakstan (wild guess, forgive the spelling). Heard there is a 76 out there. Not sure how hot it gets there in summer, but it sure does get cold in winter!!
139 has potential, once they start spitting them out of the factory at a reasonable speed, and there is a possibility that one will be heading FSU way soon (ish).
noooby
139 has potential, once they start spitting them out of the factory at a reasonable speed, and there is a possibility that one will be heading FSU way soon (ish).
noooby
Having looked at both the 155 and 139, if your company is looking to move forward in terms of performance (Safety), the only choice you have is the 139!! At present the 155 offers nothing that you do not already get from the 76 apart from the fact that you can say you have new technology.